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sin(x)=sqrt(2)*cos(x)^(2) la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
           ___    2   
sin(x) = \/ 2 *cos (x)
$$\sin{\left(x \right)} = \sqrt{2} \cos^{2}{\left(x \right)}$$
Solución detallada
Tenemos la ecuación
$$\sin{\left(x \right)} = \sqrt{2} \cos^{2}{\left(x \right)}$$
cambiamos
$$\sin{\left(x \right)} - \sqrt{2} \cos^{2}{\left(x \right)} = 0$$
$$- \sqrt{2} \left(1 - \sin^{2}{\left(x \right)}\right) + \sin{\left(x \right)} = 0$$
Sustituimos
$$w = \sin{\left(x \right)}$$
Abramos la expresión en la ecuación
$$w - \sqrt{2} \left(1 - w^{2}\right) = 0$$
Obtenemos la ecuación cuadrática
$$\sqrt{2} w^{2} + w - \sqrt{2} = 0$$
Es la ecuación de la forma
a*w^2 + b*w + c = 0

La ecuación cuadrática puede ser resuelta
con la ayuda del discriminante.
Las raíces de la ecuación cuadrática:
$$w_{1} = \frac{\sqrt{D} - b}{2 a}$$
$$w_{2} = \frac{- \sqrt{D} - b}{2 a}$$
donde D = b^2 - 4*a*c es el discriminante.
Como
$$a = \sqrt{2}$$
$$b = 1$$
$$c = - \sqrt{2}$$
, entonces
D = b^2 - 4 * a * c = 

(1)^2 - 4 * (sqrt(2)) * (-sqrt(2)) = 9

Como D > 0 la ecuación tiene dos raíces.
w1 = (-b + sqrt(D)) / (2*a)

w2 = (-b - sqrt(D)) / (2*a)

o
$$w_{1} = \frac{\sqrt{2}}{2}$$
$$w_{2} = - \sqrt{2}$$
hacemos cambio inverso
$$\sin{\left(x \right)} = w$$
Tenemos la ecuación
$$\sin{\left(x \right)} = w$$
es la ecuación trigonométrica más simple
Esta ecuación se reorganiza en
$$x = 2 \pi n + \operatorname{asin}{\left(w \right)}$$
$$x = 2 \pi n - \operatorname{asin}{\left(w \right)} + \pi$$
O
$$x = 2 \pi n + \operatorname{asin}{\left(w \right)}$$
$$x = 2 \pi n - \operatorname{asin}{\left(w \right)} + \pi$$
, donde n es cualquier número entero
sustituimos w:
$$x_{1} = 2 \pi n + \operatorname{asin}{\left(w_{1} \right)}$$
$$x_{1} = 2 \pi n + \operatorname{asin}{\left(\frac{\sqrt{2}}{2} \right)}$$
$$x_{1} = 2 \pi n + \frac{\pi}{4}$$
$$x_{2} = 2 \pi n + \operatorname{asin}{\left(w_{2} \right)}$$
$$x_{2} = 2 \pi n + \operatorname{asin}{\left(- \sqrt{2} \right)}$$
$$x_{2} = 2 \pi n - \operatorname{asin}{\left(\sqrt{2} \right)}$$
$$x_{3} = 2 \pi n - \operatorname{asin}{\left(w_{1} \right)} + \pi$$
$$x_{3} = 2 \pi n - \operatorname{asin}{\left(\frac{\sqrt{2}}{2} \right)} + \pi$$
$$x_{3} = 2 \pi n + \frac{3 \pi}{4}$$
$$x_{4} = 2 \pi n - \operatorname{asin}{\left(w_{2} \right)} + \pi$$
$$x_{4} = 2 \pi n + \pi - \operatorname{asin}{\left(- \sqrt{2} \right)}$$
$$x_{4} = 2 \pi n + \pi + \operatorname{asin}{\left(\sqrt{2} \right)}$$
Gráfica
Respuesta rápida [src]
     pi
x1 = --
     4 
$$x_{1} = \frac{\pi}{4}$$
     3*pi
x2 = ----
      4  
$$x_{2} = \frac{3 \pi}{4}$$
           /    /  ___        \\         /    /  ___        \\
           |    |\/ 2 *(1 - I)||         |    |\/ 2 *(1 - I)||
x3 = - 2*re|atan|-------------|| - 2*I*im|atan|-------------||
           \    \      2      //         \    \      2      //
$$x_{3} = - 2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 - i\right)}{2} \right)}\right)} - 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 - i\right)}{2} \right)}\right)}$$
           /    /  ___        \\         /    /  ___        \\
           |    |\/ 2 *(1 + I)||         |    |\/ 2 *(1 + I)||
x4 = - 2*re|atan|-------------|| - 2*I*im|atan|-------------||
           \    \      2      //         \    \      2      //
$$x_{4} = - 2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 + i\right)}{2} \right)}\right)} - 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 + i\right)}{2} \right)}\right)}$$
x4 = -2*re(atan(sqrt(2)*(1 + i)/2)) - 2*i*im(atan(sqrt(2)*(1 + i)/2))
Suma y producto de raíces [src]
suma
                  /    /  ___        \\         /    /  ___        \\         /    /  ___        \\         /    /  ___        \\
pi   3*pi         |    |\/ 2 *(1 - I)||         |    |\/ 2 *(1 - I)||         |    |\/ 2 *(1 + I)||         |    |\/ 2 *(1 + I)||
-- + ---- + - 2*re|atan|-------------|| - 2*I*im|atan|-------------|| + - 2*re|atan|-------------|| - 2*I*im|atan|-------------||
4     4           \    \      2      //         \    \      2      //         \    \      2      //         \    \      2      //
$$\left(- 2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 + i\right)}{2} \right)}\right)} - 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 + i\right)}{2} \right)}\right)}\right) + \left(\left(\frac{\pi}{4} + \frac{3 \pi}{4}\right) + \left(- 2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 - i\right)}{2} \right)}\right)} - 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 - i\right)}{2} \right)}\right)}\right)\right)$$
=
         /    /  ___        \\       /    /  ___        \\         /    /  ___        \\         /    /  ___        \\
         |    |\/ 2 *(1 + I)||       |    |\/ 2 *(1 - I)||         |    |\/ 2 *(1 + I)||         |    |\/ 2 *(1 - I)||
pi - 2*re|atan|-------------|| - 2*re|atan|-------------|| - 2*I*im|atan|-------------|| - 2*I*im|atan|-------------||
         \    \      2      //       \    \      2      //         \    \      2      //         \    \      2      //
$$- 2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 + i\right)}{2} \right)}\right)} - 2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 - i\right)}{2} \right)}\right)} + \pi - 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 + i\right)}{2} \right)}\right)} - 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 - i\right)}{2} \right)}\right)}$$
producto
        /      /    /  ___        \\         /    /  ___        \\\ /      /    /  ___        \\         /    /  ___        \\\
pi 3*pi |      |    |\/ 2 *(1 - I)||         |    |\/ 2 *(1 - I)||| |      |    |\/ 2 *(1 + I)||         |    |\/ 2 *(1 + I)|||
--*----*|- 2*re|atan|-------------|| - 2*I*im|atan|-------------|||*|- 2*re|atan|-------------|| - 2*I*im|atan|-------------|||
4   4   \      \    \      2      //         \    \      2      /// \      \    \      2      //         \    \      2      ///
$$\frac{\pi}{4} \frac{3 \pi}{4} \left(- 2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 - i\right)}{2} \right)}\right)} - 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 - i\right)}{2} \right)}\right)}\right) \left(- 2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 + i\right)}{2} \right)}\right)} - 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 + i\right)}{2} \right)}\right)}\right)$$
=
      /    /    /  ___        \\     /    /  ___        \\\ /    /    /  ___        \\     /    /  ___        \\\
    2 |    |    |\/ 2 *(1 + I)||     |    |\/ 2 *(1 + I)||| |    |    |\/ 2 *(1 - I)||     |    |\/ 2 *(1 - I)|||
3*pi *|I*im|atan|-------------|| + re|atan|-------------|||*|I*im|atan|-------------|| + re|atan|-------------|||
      \    \    \      2      //     \    \      2      /// \    \    \      2      //     \    \      2      ///
-----------------------------------------------------------------------------------------------------------------
                                                        4                                                        
$$\frac{3 \pi^{2} \left(\operatorname{re}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 - i\right)}{2} \right)}\right)} + i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 - i\right)}{2} \right)}\right)}\right) \left(\operatorname{re}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 + i\right)}{2} \right)}\right)} + i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{\sqrt{2} \left(1 + i\right)}{2} \right)}\right)}\right)}{4}$$
3*pi^2*(i*im(atan(sqrt(2)*(1 + i)/2)) + re(atan(sqrt(2)*(1 + i)/2)))*(i*im(atan(sqrt(2)*(1 - i)/2)) + re(atan(sqrt(2)*(1 - i)/2)))/4
Respuesta numérica [src]
x1 = 52.621676947629
x2 = 8.63937979737193
x3 = 27.4889357189107
x4 = 2.35619449019234
x5 = -18.0641577581413
x6 = -79.3252145031423
x7 = -73.0420291959627
x8 = 19.6349540849362
x9 = 33.7721210260903
x10 = 38.484510006475
x11 = -11.7809724509617
x12 = 69.9004365423729
x13 = 71.4712328691678
x14 = -87.1791961371168
x15 = 88.7499924639117
x16 = -62.0464549083984
x17 = -16.4933614313464
x18 = -10.2101761241668
x19 = -43.1968989868597
x20 = 32.2013246992954
x21 = 46.3384916404494
x22 = -5.49778714378214
x23 = -49.4800842940392
x24 = 76.1836218495525
x25 = 82.4668071567321
x26 = 429.612795378404
x27 = -98.174770424681
x28 = 90.3207887907066
x29 = -54.1924732744239
x30 = 63.6172512351933
x31 = -24.3473430653209
x32 = -35.3429173528852
x33 = -3.92699081698724
x34 = -85.6083998103219
x35 = -47.9092879672443
x36 = -55.7632696012188
x37 = -93.4623814442964
x38 = 25.9181393921158
x39 = 40.0553063332699
x40 = 0.785398163397448
x41 = -91.8915851175014
x42 = -68.329640215578
x43 = 77.7544181763474
x44 = 96.6039740978861
x45 = -99.7455667514759
x46 = 84.037603483527
x47 = -60.4756585816035
x48 = 44.7676953136546
x49 = -41.6261026600648
x49 = -41.6261026600648